Portable computer terminals typically have a base with the keys and a cover rotationally coupled to the base. The cover often includes an LCD display to show the information placed into the terminal's memory either through the keys or through an input/output port. Accordingly, the cover, as a consequence, possesses appreciable inherent weight.
However, the use of the portable terminal requires the placement of the cover at an orientation relative to the base that will permit the facile viewing of the display. Local light conditions and the height of the user will determine the precise angle of the cover at which the proper viewing may occur.
Various mechanisms have found use to hold the cover at a desired angle relative to the base. Some make use of positive stops to prevent the cover from moving out of the desired position. However, the lack of infinite adjustability often means that the cover cannot remain at the optimum viewing angle for a particular environment.
Other mechanisms attempt to achieve a frictional retention of the cover relative to the base. However, the weight of the cover sits to one side of the axis of rotation. Accordingly, it generally has a substantial torque created by the pull of gravity. It thus shows a tendency to rotate towards the ground. Often, the friction mechanism does not possess sufficient strength to hold the cover at a desired position other than substantially vertical. However, again a substantially vertical orientation may not prove optimal for the proper viewing of the display.
Accordingly, the search continues for a mechanism that will hold the cover of a portable computer terminal at a particular desired angle relative to the base. This mechanism should have sufficient strength to retain the cover at its selected position even where that position lies away from the vertical plane. Moreover, the mechanism should generally permit infinite variability in the rotational position of the cover relative to the base.